The first organocatalytic asymmetric [3 + 2]-annulation of γ-sulfonamido-α,β-unsaturated ketones with cyclic Nsulfimines has been developed, and enantioenriched functionalized polyheterotricyclic imidazolidines were obtained in good yields and with excellent enantioselectivities. This approach was also extended to the asymmetric [3 + 2]-annulation of γ-hydroxy-α,βunsaturated ketones, affording enantioenriched polyheterotricyclic oxazolidines. In addition, base-catalyzed [3 + 2]-annulations of γsulfonamido/γ-hydroxy-α,β-unsaturated ketones with cyclic N-sulfimines were re-investigated under mild reaction conditions for the synthesis of racemic polyheterotricyclic imidazolidines and oxazolidines with excellent diastereoselectivities.

The first asymmetric synthetic method for enantioenriched 1,3‐oxazinane and hexahydropyrimidine derivatives via the asymmetric [4+2]‐annulation of cyclic N‐sulfimines has been established. The reaction of cyclic N‐sulfimines with δ‐hydroxy‐α,β‐unsaturated ketones afforded a wide range of enantioenriched polyheterotricyclic 1,3‐oxazinane derivatives in high yields with good to excellent enantioselectivities in the presence of a cinchonidine‐derived squaramide catalyst. This approach has been extended to the asymmetric organocatalytic [4+2]‐annulation of cyclic N‐sulfimines with δ‐NHTs‐α,β‐unsaturated ketones providing enantioenriched hexahydropyrimidines. In addition, the asymmetric [4+2]‐annulation of δ‐hydroxy‐ and δ‐NHTs‐α,β‐unsaturated ketones gave their corresponding enantioenriched 1,3‐oxazinane and hexahydropyrimidine derivatives with different absolute configurations.

A highly efficient and straightforward synthetic methodology has been established for the preparation of imidazolidine derivatives through the [3 + 2]‐annulation of cyclic N‐sulfimines. This reaction involves the reaction of cyclic N‐sulfimines and γ‐sulfonamido‐α,β‐unsaturated carbonyl compounds, with Cs2CO3 serving as the catalyst. The outcome is a diverse range of imidazolidine derivatives with remarkable yields and stereoselectivities. In addition, the [4 + 2]‐annulation between cyclic N‐sulfimines and δ‐sulfonamido‐α,β‐unsaturated carbonyl compounds, catalyzed by Et3N, has been successfully applied for the synthesis of stereoselective hexahydropyrimidines. Furthermore, the base‐catalyzed annulation of cyclic N‐sulfimines with γ‐ and δ‐hydroxy‐α,β‐unsaturated carbonyl compounds has proven to be a reliable method for the synthesis of oxazolines and 1,3‐oxazinanes.